Refrigerating system



April 22, 1941. i w. H. F. SCHMIEDXNG 2,239,583

REFKIGERAfII-NG SYSTEM v Filed July '1, 19:58 4 Sneets-Sheot 2 I A ril22, 1941. w. H. F. SCHMIEDING REFRIGERATING SYSTEM Filed July 7, 1938 4Sheets-Sheet 3 Jig 7 ,(mv o April 1941- w. H. F. scumzumd 2, 39,583

REFRIGBRATING SYSTEM Filed Jul '7, 1938 4 Sheets-Sheat 4 Ark. m2 "3 oftheinvention;

Patented Apr.

i UNITED STATES" PATENT. OFFICE I i nnraicsi ati izc i srs'rnm Warren H.F. Schmieding, Columbus, Ohio Application 7, 1938, Serial N0. 217,873

The present invention relates to refrigerating systems wherein aplurality of heat absorbers are associated with a single heat dissipatorfor cooling the absorbers and particularly to that type of system inwhich one of the heatabsorbers is maintained at a relatively coldtemperature for freezing or storing frozen products and the other ismaintainedat a relatively higher temperature 1 in response to a demandfor refrigeration on the relatively cold heat absorber.

Fig. 7 is a cross sectional view of one of the valvesemployed in Fig. 6;and

' 23 and 2| and a heat -dissipator 22. The heat Another object of thepresent invention is to 7 provide a refrigerating system utilizing aplurality of evaporators connected in series circuit relationandcontrolling the pressure differential between the evaporators inresponse to a demand for refrigeration on the relatively coldevaporator.

of the evaporators when it is desirable to remove absorbers are hereinshown as evaporators and the heat dissipator includes a compressor 24which is driven by a motor 25 and belt 26. The heat dissipator alsoincludes an air cooled condenser 23 which is connected with the highpressure side of the compressor by a pipe 29. Liquid refrigerant isconveyed to pressure reducing valves 3i and 32 by a pipe 33. Thepressure reducing valves each include a casing 35 containing a float 36which actuates a needle valve 31. When a predetermined amount of liquidis contained within the casing 35, the float 36 rises oil of its seat 38and admits liquid refrigerant in the case of valve 3i, to pipe 43 and,in the case of valve 32, to the pipe 4|. The pipe 40 is connected to theheader 43 of evaporator 20 and the pipe 4! is connected to theheader':.44 of evaporator 2|. The evaporators are'preferably of thesheet metal type now generallyused in'the refrigerating industry-andinclude two sheets of metal hermetically joined with one another, one ofwhich being corrugated whereby to provide a plurality of ducts extendinghorizontally from either header 43 or header 44 and vertically to thefrost therefrom.

reducing valve employed in the system shown inFig, 1;

' to the low pressure side of the compressor 24.. Gaseous refrigerant iswithdrawn from evapoi headers 45 and 41 of evaporators 20 and 2!,respectively. Gaseous refrigerant is withdrawn from evaporator 20through pipe. 43 which is connected with header 46. This pipe 43 isconnectedby a coupling 49 to a pipe 53. The pipe.

50 is connected to a vaporizing chamber or surge tank 5i and this tankis connected by a pipe '52 rator 2| by a pipe which is connected withthe outlet header 41. This gaseous refrigerant flows through a valve 55,whence it flows by a pipe to the coupling 45 and from coupling 43 itflows by way of pipe 55; tank 5| and'pipe 52 to the low pressure side ofcompressor 24.

Fig.3 is a cross sectional view of another con- I Fig. 6 is a.diagrammatic view-of another form of the invention;

- The valve 55 is adapted to. at times, impede ing a passage 53 forreceiving refrigerant from pipe 54 and: a passage 53 is controlled by avalve 5!. This valve is actuated by a diaphragm 63 contained in achamber 54. when the valve is as closed the flow of refrigerant fromevaporator 2| is stopped. It may be desirable, however, to permit asmall quantity of gaseous refrigerant to escape from evaporator 2| andfor this purpose I have. provided a restricted by-pass 65 whichinterconnects passage 59 with the passage 60 so that a limited amount ofrefrigerant may be withdrawn from evaporator 2| although valve 6| isclosed. The valve BI is actuated by a thermostatic system 66 including abulb 61 and pipes 68 and 69 connected by a coupling I0.

- This thermostatic system also includes the chamber 64. Thethermostatic system contains a volatile fluid and the charge is suchthat when the bulb is at or above 32 deg. F., the pressure in the systemis sufficient to collapse the diaphragm 63 and close the valve 6| on itsseat.

Thus it is apparent that when warm foods or water, adapted to be frozen,are placed within the storage chamber 1| of evaporator 20, thethermostaticsystem 66 will function to stop or impede the flow ofgaseous refrigerant from evaporator 2|. In that event the withdrawingaction of .the compressor will be concentrated or primarily concentratedon withdrawing gaseous refrigerant from evaporator 20. This willcontinue until the evaporator 20 and the food stored therein have beenreduced to the desired low temperature at which time the pressure willhereducedin the thermostatic system 66 to open the valve 6| whereby therefrigerating system will be returned to normal operation.

It is desirable to normally maintain the evaporator 2| above thetemperature of evaporator 20, the purpose being to maintain theevaporator 2| merely slightly below the desired temperatur of the airandthe foodproducts so as to limit or substantially prevent dehydration ofthe food products such as vegetables' This normal differential intemperature between evaporator 20 and 2| is obtained by making theevaporator 2| much larger than the evaporator 20, insulating theevaporators from one another by insulation 13 and providing arestriction I2 in outlet pipe 54 of evaporator 2|.

Preferably the temperatures are controlled by thermostatic controlsystem 14 including a bulb I5, a diaphragm I6 and snap acting mechanism11, which controls the switch 18. The switch I8 controls the startingand stopping of the motorporized refrigerant from evaporator 2| toevaporator 20 will be stopped or impeded to such an extent thatsubstantially no condensation will take place in evaporator 28. Whenthis occurs the evaporator, 21 will increase in temperature rapidly.When the temperature of the air within the compartment 84 increases:beyond that desired, thermostatic system I4 will function to close theswitch I8 to start the compressor 24. Preferablythe bulb I is connectedin intimate metallic contact with the wall of the evaporator so as to beresponsive to the temperature thereof. Thus it is apparent thatwhen warmfood is contained within evaporator and there is a demand forrefrigeration by evaporator 20, the thermostatic system I4 will functionto start the compressor.-

If desirable another thermostatic system 86 may be employed which willinclude in part, thermostatic system 66 for valve 6|; namely, it willinclude bulb 61, pipe and coupling I0 and will also include a pipe 81, adiaphragm 88 which actuates snap acting mechanism 89 for actuating aswitch 90. This switch 90is connected in parallel with switch I8. It is:arranged to directly close the motor circuit when the bulb 61 functionsto close valve 6 I. The thermostatic system I4 will maintain thecompressor operative until the temperature of the evaporator 2| has beendecreased to its desired normal low temperature and it is quiteapparent'that this relatively low temperature will not be attained untilthe demand for refrigeration on evaporator 2|) has been satisfiedbecause, until the demand on evaporator 28 is satisfied, the valve 6|will be maintained closed, and due to the fact that the compressor isconcentrating or substantially concentrating on evaporator 20, theevaporator 2| will not be reduced to desired temperature untilevaporator 20 is satisfied. If thermostatic system 86 is also employed,thermostatic system I4 will nevertheless maintain the compressor inoperation until evaporator 2| has been satisfied.

Thus it is apparent that thermostatic system 86 may be omitted forthesake of reduction in cost of the apparatus. It does, however, havethe effect of starting the compressor quickly in response to a demandfor refrigeration by evaporator 20.

From the foregoing it will be seen that the evaporators 20 and 2| aremaintained at the desired temperatures substantially at all times andthat evaporator 2| will not ordinarily be reduced Y to a temperaturewhich is too cold for the proper preservation of food products such asvegetables even though there is an extensive demand on evaporator 20which would require a continuous or substantially continuous operationof comous refrigerant from evaporator 2| is stopped or impeded to suchan extent that the temperature throughout will not be reduced beyondthat normally desired.

The compartment 'II of evaporator 20 is preferably divided, into a foodstorage compartment 92 for frozen foods and an ice freezing compartment93.

In the embodiment illustrated in Fig. 4 one part .of a secondary systemwhich is cooled by evaporator I20. In this embodiment the evaporator I28is constructed similar to evaporator 20 and evaporator |2I is similartorevapo'rator 2| ,except that the upper header I4'I of the evaporatorI2| extends downwardly merely for convenience. In this embodiment thewell known v resister type pressure reducer |3I is employed comprising along spiral having a very small inside diameter. Refrigerant iswithdrawn from the upper header I46 to the low pressure side of thecompressor 24 by a pipe I48 and the condensed refrigerant fromcondenser-receiver I28 is conducted by the pipe I33 to the restrictorI8I. Like in Fig. l, the evaporator I28 is the low temperatureevaporator for freezing water and storing frozen foods and is supportedin insulation I13. The secondary system includes a condenser I50 whichis in intimate heat exchange relation pressor 24. During this period,the flow of gase-' of the heat absorbers I20 is illustrated as an.evaporator and the other heat absorber I2| is e of the compressor.

with a side wall of evaporator I20. The condensed refrigerant flows fromthe low part thereof by a pipe II to a valve I55 and the outletof thevalve I55 is connected with the header I44 of evaporator I2I. The inletof condenser I50 is connected by apipe I50 to the outlet header I41 ofthe evaporator I2I. The valve I55 is substantially the same as valve 55of Fig. 1 except that it is inverted. It includes a valve body I50forming passages I50 and I60 which are controlled by a valve I6Iactuated by a diaphragm I63. This diaphragm I63 is contained within aclosed chamber I64 and is actuated by a thermostatic system I66including a bulb'I01, and a pipe I60, which is connected with thechamber I64. The bulb I61 is disposed within the storage compartment I1Iof evaporator I and if desirable it may be placed in intimate metalliccontact with an ice tray'support I12.

- When warm water or relatively warm food is placed in the compartment"I, the volatile fluid in the thermostatic system I66 will expand andcause the valve .I6I to close to impede or stop the flow of liquid incondenser I50 to the header I4'4-of evaporator I2I. when circulationthrough the secondary system is'stopped or impeded, less heat will bewithdrawn from the condenser I50 to'the evaporator I20 and therefore theevaporator I20 concentrates its cooling eflect'upon the products storedwithin the compartment "I.

In this system, like that shown in Fig. 1, the motor is started andstopped by the closing andopeningof a switch 10 which is controlled bythe same type of thermostatic system 14 as is employed inFig. 1. Whenthe temperature of the evaporator I2I attains a predetermined high valuethe switch 10 will be closed and remain closed untfl the evaporator iscooled to a predetermined low value; When there is a demand forrefrigeration by evaporator. I20, the valve I55 will be closed or theflow of refrigerant therethrough will be impeded causing the temperatureof evaporator I2I to increase to start the motor. "When the demand fromevaporator I20 is satisfiechvalve I55 will be opened widely and therefrigerating system will be maintained operative until temperature ofevaporator I2I is satisfied at which time, it will operate to stop themotor. If desirable, valve I55 may be provided with a restricted by-passI65 interconnectto a pressure reducing valve 232 whence it flows by pipe2 to the header 244 of evaporator 22I. The refrigerant first passesthrough evaporator 22I to its header 241 whence it flows by a pipe 239through a pipe 240 and empties into the header 243 of evaporator 220.Refrigerant after passing through evaporator 220 flows from the header246 through a pipe 240 to the low pressure side Preferably the valve mf'differential type, that is it includes a casing 235 containing aweighted valve 231. Pressure in the through a pressure reducing valve23I.

mates high pressure side lifts the valve off its seat to permit the flowof liquid refrigerant from the pipe 230 to pipe, 24I.- When thedifferential in pressure in pipe 203 is at a predetermined value withrespect to the pressure within the evaporator 22I, the weighted valve231 is lifted off its seat to admit more refrigerant to the evaporator22I. I I

, Valve 23I. is also of the pressure differential type and one formthereof is shown in Fig. 'l in which the'casing 250 is connected withpipes 230 and 240. A passage 250 is connected with the pipe 239 and theflow of refrigerant through the passage iscontrolled by a ball valve26I. This ball valve 26I is weighted by upper and lower discs 264connected with one another by three spacers 265. Valve 26I is lifted ofiits seat by pressure within thepipe 239 and the pressure at which valve"26I is opened is controlled by the weight of valve 26I the discs 264.andspacers 265 as one factor and pressure of a thermostatic system 266 asanother factor. This thermostatic system 266 includes a bulb 261, a pipe268 and a bellows type diaphragm 263. .An increasev in pressure in thethermostatic system 266 causes an increase in. the closing pressure ofthe valve 26I, the force being transmitted from the bellows 263 to-thetop of the uppr disc 264 through a spring 210. The valve 23I is balancedfor changes in pressure within the low pressure side of the valve by asecond bellows 214 and a spring 215 which latter is interposed betweenthe bellows 214 and the lower disc 264. Thus it is apparent that thevalve 26I is notaflected by mere change in the pressure'in the lowpressure side of casing 250 but raised off its seat by an increase inpressure differential between the pressure above and below the valve.This pressure differential is varied by the pressure'in the thermostaticsystem 266.

Obviously since the pressure within the evaporator 220 is less than thepressure in evaporator 22I and the inner evaporator 220 is insulated byinsulation 213 the former is maintained relatively colder. The valve isso adjusted thatevaporator 22I is maintained considerably above freezingtemperature while the evaporator 220 is maintained below water freezingtemperature.-

When warrn water or unfrozen foods are placed within the compartment 21Iof evaporator 220,

thermostatic system 266 will function to in- 1 pressure and temperaturewithin evaporator 22I will be increased. e e

Like'in Figs. 1 and 4 the motor is controlled by a thermostatic system14 which actuates a' switch 10. 'This switch 10 includes a thermostaticbulb 15 placed in intimate heat exchange relation with the evaporator22I. It is apparent therefore that when relatively warm products are isof the pressure 220 and since the refrigerating effect of evaporator 22Iis decreased the thermostatic system '14 will not function to shut offto interrupt the motor circuit until after the demand on evaporator 220has first been satisfied and then only 'after the evaporator 22I hasbeen reduced to its er 346 the refrigerant flows by a pipe 339' througha valve 355 and pipe 348 to the header 344 of evaporator 32!. ofevaporator 32! is connected by the pipe 348 to the low pressure side ofthe compressor. The inner evaporator 320 is insulated from the outerevaporator 32! by insulation 313 and since it is insulated and since itis the first to receive the liquid refrigerant, it is maintained at arelatviely colder temperature than the evaporator 32!. The constructionof the arrangement is such that normally evaporator 32!! is maintainedbelow freezing temperature while evaporator 32! is maintained slightlybelow the temperature of the surrounding air and the temperature of thefood to be refrigerated.

Due to the fact that" evaporator 320 is maintained at a relatively lowtemperature, moisture from the air and food stored therein will condenseupon the walls thereof and the evaporator will become frosted and impairthe efllciency thereof. Therefore it is desirable to, at times, defrostevaporator 32!) and a valve 355 is provided for this purpose. In theembodiment illustrated the valve is in its defrosting position in whichitwill be seen that the liquid refrigerant will flow through a conduitwhich by-passes; the restrictor 33!. This by-pass includes a pipe 359and a pipe 362. The pipe 359 is also connected with the pipe 333 and thepipe 362 is also connected with the header 343 of evaporator 328.

The flow of refrigerant from passage 360 and 36! is controlled by avalve 364. This valve is carried by a rod 318. Rod 31!) is coupled witha rod 31! having a pull knob 312 thereon. A spring coupling isinterposed between rod 31! and 310 including a spring 313 which normallyurges the rod 310 to the right when the valve is I in the positionshown.

' The valve 355 also includes a chamber 315 which is separated fromchamber 36! by a diaphragm 316. The valve 355 also includes a chamber311 which is sealed from the exterior and to rod 316 by a diaphragm 316.The flow of refrigerant from chamber 311 to chamber 315 is alsocontrolled by the valve 364, that is when the chambers 360 and 36! arein communication, the passage between chambers 311 and 315 is closed,and vice versa, when the valve is in the opposite position. The rod 31!carries an abutment 319 and a spring 389 is interposed between theabutment 319 and an end wall of the valve 355 d normally urges the rod31! to the left.

The rod 31! is held in the position shown by a.

latch 382. When the latch 382 is withdrawn, the spring 389 forces therod 31! and the rod 310 to the extreme left whereby the passage betweenchambers 360 and 36! is closed and the passage between chambers 311 and315 is opened.

A thermostatic system 366 is employed for releasing, the latch 332..This thermostatic system includes a bulb 361 and a diaphragm containedThe outlet header 341 within housing 363. The housing 363 is connectedwith the bulb 361 by a pipe 368.

When the valve is in the position shown; namely, in the defrostingposition, the high pressure refrigerant will flow from the condenserreceiver 328 through pipes 333 and 359, chambers 368 and 36! and pipe362 to the header 343 of evaporator 320. The refrigerant will first flowthrough the evaporator and out of the header 346 thence into the pipe339 whence it will flow by a pipe 384 through a restrictor type pressurereducer 332 and into the header 344 of evaporator to be melted. It willalso be noted that at this.

time refrigerant cannot pass through the bypass including the lower partof pipe 339, chambers 311' and 315 of valve 355 and pipe 344 but mustflow through the restrictor 332.

The thermostatic system 366 contains a freezing substance such as waterwithin the bulb 361 and oil within the pipe 368 and the chamber 363.When the ice within bulb 361 melts, the pressure will be decreasedwithin the thermostatic system causing the latch 382 to be releasedwhereby the spring 38!] will cause the valve 364 to close the passagebetween chamber 368 and 36! and open the passage between chambers 311and 315 whereby the system will be reduced to normal.

The evaporator 32!! may be defrosted by merely pulling outwardly on theknob 312 and the latch 382 will hold the rods 310 and 31! in theposition shown. The defrosting operation will take place quickly in viewof the fact that the ice will be melted by the heat of the high pressurerefrigerant. In other words, during the defrosting operation the quickfreezing evaporator 32!] functions as a condenser for a refrigeratingsystem in which the air cooling type of evaporator is the otherevaporator of the system. When the ice is melted, the pressure will bereduced in thermostatic system 366 and the latch 382 will be retracted.Thus the system is returned to normal automatically.

A thermostatic system like 86 of Fig. 1 may be employed for starting andstopping'the compressor in accordance with the temperature of the lowtemperature evaporator 328. In the preferred embodiment the compressormotor 25 is controlled by a thermostatic system 14 like that shown inFig. 1.

While the forms 'of embodiments of the present invention as hereindisclosed constitute preferred forms, it is to be understood that otherforms might be adopted, all coming within the scope of the claims whichfollow:

1. A refrigerating system comprising in combination, a plurality of heatabsorbers, one of which provides a relatively low temperature forfreezing and storing frozen products and another provides a relativelyhigher temperature for maintaining poducts above freezing temperature, aheat dissipator associated with the heat absorbers for removing heatfrom the latter including a fluid conduit continuously open while theheat dissipator is operating for the circulation of refrigerant throughthe second mentioned heat absorber, means responsive to a temperatureslightly above 32 Deg. F. of the environment affected by the firstmentioned heat absorber for varying the rate of removal of heat unitsfromthe first mentioned heat absorber.

2. A refrigeratin system comprising in combination, a plurality of heatabsorbers, one of which provides a relatively low temperature forfreezing and storing frozen products and another I provides .arelatively higher temperature 'for maintaining products above freezingtemperature, a heat dissipator associated with the heat absorbers forremoving heat from the latter including a fluid conduit continuouslyopen while the heat dissipator is operating for the circulation ofrefrigerant through the second'mentioned heat absorber, means responsiveto. a tempera ture slightly above 32 Deg. F. of the environment affectedby the first mentioned heat absorber for increasing the removal of heatunits from the first mentioned heat absorbers and decreasing the removalof heat units from the second mentioned heat absorbers.

13. A refrigerating system comprising in combination, aplurality of heatabsorbers, one of which provides a relatively low temperature for.

freezing and storing frozen products and another maintaining productsabove freezing temperature, a heat dissipator associated with theheatabsorbers for removing heat from the latter including a fluidconduit continuously, openwhile provides a relatively higher temperaturefor l .the heat dissipator is operating for thecirculaslightly above 32Deg. F. of the first mentioned heat absorber for varying the effects ofthe heat absorbers. t

. 4. The method-of refrigeration which consists in-withdrawing heat froma plurality of evaporators by a heat dissipator at such rates that onetion of refrigerant through the second mentioned heat absorber, meansresponsive to a temperature above water freezing temperature, andincreasing the rate of volatilization in the first mentioned evaporatorby restricting circulation of refrigerant through the secondmentionedevaporator in response to an increased demand for refrigeration on thefirst mentioned evaporator.

8. The method of refrigerating in that type of system in which afreezing type heat absorber and an air cooling type heat. absorber areem-- ployed and in which it isldesirable to defrost the freezing typeheat absorber at times, which methconnectedin series, a regulating valvefor con-' trolling the flow of refrigerant from the air cooling typeevaporator to the freezing type evaporator, means for withdrawinggaseous refrigerant from the freezing type evaporator and for condensingthe refrigerant and for delivering the same to the air cooling typeevaporator, pressure reducing mechanism between said means and said aircooling type evaporator, and means responsive to the temperature of theenvironment affected by the freezing type evaporator for controllingsaid regulating valve. a

10. A refrigerating system comprising in combination, a heat dissipator,a freezing type heat absorber and an air cooling type heat absorberconnected in parallel circuit relation with respect to one another andeach in series circuit relation of the evaporators is reduced to belowwater freezing temperature and the other is maintained, at least part ofthe time, above water. freezing temperature, and increasing vaporizationinthe first mentioned evaporator while vaporizing liquid refrigerantin-the second mentioned evaporator and decreasing vaporization in thesecond mentioned evaporator in-re'sponse to an increased demand forrefrigeration on the first mentioned evaporator.

5. The method asdeflned in claim 4 including the step of decreasingvaporization in the first mentioned evaporator when the increased demandfor refrigerationis satisfied. I, I 6. The method ofrefrigerationwhich-consists in withdrawing heat from a plurality of heatabsorbers by a heat dissipator, having a limited capacity, at such ratethat one of the heat absorbers is reduced to below water freezing.temperature and the other is maintained, at least part of the time,above water freezing temperature, and concentrating the withdrawingeffect of the heat dissipator upon the first mentioned with respect to'the heat dissipator, means for varying the rateof flow of refrigeratingmedium through the air cooling type heat absorber, and

. means responsive to temperature of the environment afiected by thefreezing type heat absorber for actuating the first mentioned means.

.11. A refrigerating system comprising in combination, a heatdissipator, a freezing type heat absorber and an air cooling type heatabsorber connected in series circuit relation with one ana other andwith the heat dissipator, means for controlling the flow ofrefrigerating medium from one to the other of said heat absorbers andmeans I responsive to temperature of the environment effectv by thefreezing type heat absorber for actuating the first mentioned means.

' 12. A refrigerating system comprising in com bination, a heatdissipator, a freezing type heat absorber and an air cooling type heatabsorber connected in series circuit relation with one another and withthe heat dissipator, means for varying the flow of refrigerating mediumthrough the aircooling type heat absorber, and means heat absorber byrestricting the withdrawing effect of the heat dissipator upon thesecond mentioned heat absorber in response to an increased demand forrefrigeration on the first mentioned heat absorber.

'7. The method of refrigeration which consists in vaporizing volatilerefrigerant in a pluralltyof evaporators by'a refrigerant circulatingand heat dissipating means, having a limited capacity, at such rate thatone of the evaporators is reduced to below water freezing temperature,and

the other is maintained, at least part of the time,

responsive to temperature of the environment afi'ectedby the freezingtype heat absorber ,for actuating the first mentioned means.

13. A refrigerating system comprising in combination, a freezing typeheat'absorber and an air coolingtypeheat absorber, a heat dissipatorassociated with the absorbers for reducing the freezing type heatabsorber to below 32 deg. F.

and for maintaining the air cooling type heat absorber, at. least attimes, above 32 deg. F., means for varying the rate of fiow ofrefrigerating medium through the air cooling type heat absorber, andmeans responsive'to temperature sition, connecting the absorbers withthe heat cooling type evaporator; pressure reducing means at the inletsof each of said evaporators; a bypass for each of the means; valve meanshaving dissipator for causing cooling of the absorbers, 10

- and when in the other position, connecting the absorbers in serieswith one another and in series with the heat dissipator','said lastconnection providing a path for the flow of refrigerant to the freezingtype absorber at a temperature above 5 32 deg. F. for heating the saidfreezing type absorber; and means responsive to the temperature of theenvironment affected by the freezing type absorber for actuating thevalve means.

15. A refrigerating system comprising in combination, a freezing typevaporator; an air cooling type heat absorber; a heat dissipatorassoelated with the aforementioned elements for reducing the temperatureof the evaporator to below 32 deg. F. and for maintaining the heatabsorber, at least at times, at a temperature above 32 deg. F.; andmeans for varying'the refrigerating effect of the evaporator including avalve for varying the rate of flow of refrigerating medium twopositions, said valve means, when in one position, connecting theevaporators in series circuit relation with one of the by-passes openand the other closed, said valve means, when in another position,connecting the evaporators in series circuit relation with the firstmentioned by-pass closed and the second mentioned. bypass open,'-meansfor withdrawing refrigerant from .the evaporator last to receiverefrigerant and for compressing the same and for deliveringcompressed=refrigerant to the evaporator first to receive refrigerant;and means for controlling theyalve means.

18. The method of refrigeration in that type 'of system employing afreezing type heat absorber and an air cooling type heat absorber whichmethod consists in circulating a refrigerating medium through the heatabsorbers at such rate that the freezing type heat absorber is reducedto below water freezing temperature and the air cooling type heatabsorber is maintained, at least part of the time, above water freezingtemperature, maintaining the air cooling type heat absorber atsubstantially normal temperature and simultaneously defrosting thefreezing type heat absorber by continuing the circulation ofrefrigthrough the absorber, and a thermostatic device responsive to theenvironment afiected by the evaporator for controlling the valve.

16. A refrigerating system comprising in combination, a freezing typeevaporator and an air cooling type evaporator, said evaporators beingconnected in series, pressure reducing means connected withthe inlet ofthe air cooling type evaporator, a second pressure reducing meansinterposed between the outlet of the air cooling type evaporator and theinlet of the freezing type 40 17. A refrigerating system comprising incombination, a freezing typeevaporator and an air erant medium throughthe air cooling type heat absorber while causing the heatedrefrigerating medium to flow through the freezing type heat absorber. i

19. The method of refrigeration which consists a demand for suchtemperature on saidother evaporator.

20. The method as defined in claim 19 including the step of decreasingthe rate of heat absorption by the first mentioned evaporator when gm;increased demand'. for refrigeration is satis- WARREN H. F. SCHMIEDING.

